How to choose a stainless steel pipe
How to choose a stainless steel pipe for the job: look at four features — section, size, finish and grade. Round pipe goes for fluids, heat exchange and handrails, profile pipe for frames, fencing and furniture.
Then you calculate the diameter or section, the wall, the length and the grade for the environment.
The GCX catalogue lists 36 pipe items: 24 round and 12 profile, length 6000 mm, finishes mirror, brushed and industrial. Round pipe comes in 201, 304 and 316L, profile pipe in 201 and 304.
Round or profile
Round pipe holds pressure and washes well: there are no corners inside where product or dirt accumulates. It is taken for food lines, heat exchangers, water supply, railings and decorative posts.
Profile pipe is stiffer in bending at the same weight and gives flat faces for fasteners, glass or a panel. Square and rectangular sections go into frames, shelving, fencing, retail equipment, frames and supports.
| Type | Catalogue section | Wall, mm | Length, mm | HS code |
|---|---|---|---|---|
| Round | ⌀16–108 | 1.5–3.0 | 6000 | 730640 |
| Square | 20×20–50×50 | 1.5 | 6000 | 730661 |
| Rectangular | 40×20, 60×40 | 1.5–2.0 | 6000 | 730661 |
Codes 730640 and 730661 describe welded pipes of round and non-round section. This means the catalogue offers welded product, not seamless. The difference between welded and seamless pipe is important to understand before ordering: seamless is made to ГОСТ 9941 and 9940, it is needed for high pressure and aggressive environments, while welded covers most jobs in finishing, frames and food equipment.
Diameter, wall, length
The size is chosen from the flow rate and the load. For water and air, look at the throughput: the larger the diameter, the greater the flow at the same pressure. For load-bearing structures, the load and deflection are calculated, and here it is not the diameter that decides but the section modulus.
Small diameters 16–25 mm go into handrails, connections and decorative elements. 32–50 mm into posts, railings, frames and food lines. 76 and 108 mm into headers, tanks and industrial pipelines.
A 1.5 mm wall is the baseline for decorative and frame jobs. 2–3 mm is taken where stiffness, a thread or a welded seam under load is needed. The thinner the wall, the lighter the product and the lower the margin for wear.
| Size | Weight per 1 m, kg | Typical job |
|---|---|---|
| ⌀16×1.5 | 0.54 | handrails, décor, connections |
| ⌀25×1.5 | 0.87 | posts, railings, food lines |
| ⌀50.8×1.5 | 1.83 | frames, fencing |
| ⌀76.1×2.0 | 3.68 | headers, structures |
| ⌀108×3.0 | 7.81 | industrial pipelines |
The weight of round pipe is calculated by the formula (D − S) × S × 0.0248, where D is the outside diameter and S the wall. For profile pipe, 2 × (A + B − 2S) × S × 0.0079 is used. The density of stainless steel is about 7.9 g/cm³, the calculation gives a guide, and the exact batch weight is in the certificate.
Finish and purpose
The finishes in the catalogue are mirror, brushed and industrial. Mirror pipe goes into visible elements: handrails, posts, retail equipment, interiors. Brushed, also called satin, gives a matte tone without glare and shows fingerprints less. Industrial is for hidden structures, heat exchangers and places where appearance does not matter.
For food use, not only the grade but also the cleanliness of the surface matters: a smooth pipe without pits and burrs washes faster. The weld seam must be cleaned, otherwise product remains in it.
Grade for the environment
| Grade | ГОСТ analogue | Environment | Where it is used |
|---|---|---|---|
| 201 | 12Х15Г9НД | dry, indoors | furniture, décor, indoor handrails |
| 304 | 08Х18Н10 | water, moisture, food environments | food lines, heat exchangers, outdoor railings |
| 316L | 03Х17Н14М2 | chlorides, salt, acid | marine environment, chemicals, brines |
Molybdenum in 316L holds back pitting corrosion, so for water with chlorides there is no alternative to it. Grade 201 is cheaper but not suitable for wet and aggressive environments. Austenitic pipes are weakly magnetic after annealing; magnetism is not a sign of quality and not a way to determine the grade.
Frequently asked questions
What sizes of stainless steel pipe are in the catalogue?
Round — from ⌀16 to ⌀108 mm with a wall of 1.5–3 mm. Profile — square from 20×20 to 50×50 mm and rectangular 40×20 and 60×40 mm. Length — 6000 mm, finishes mirror, brushed and industrial.
How does welded pipe differ from seamless?
Welded is made from strip with a seam, seamless from a solid billet. Seamless holds high pressure and is supplied to ГОСТ 9941 and 9940, welded is cheaper and covers most jobs in finishing, frames and food equipment.
Which grade to choose for outdoors and moisture?
For outdoors, a sink and a food line — 304. If there is sea, salt, chlorinated water or chemicals nearby, take 316L: the molybdenum in its composition slows pitting corrosion.
How to calculate the weight of a stainless steel pipe?
For round pipe: (diameter − wall) × wall × 0.0248, which gives kilograms per metre. For profile pipe: 2 × (A + B − 2 × wall) × wall × 0.0079. For example, ⌀25×1.5 gives about 0.87 kg per metre.
Which pipe is better for a handrail — mirror or brushed?
For an indoor handrail, mirror is more often taken: it is more noticeable and washes more easily. Outdoors and in public places, brushed is more practical — fingerprints, scuffs and small scratches show less on it.
Can 201 pipe be used instead of 304?
Only in a dry room where there is no moisture and no food contact. In a wet environment, outdoors and in a sink, 201 corrodes faster, so there you need 304 or 316L.
Choose pipe for the job
Browse the product range and state in the order the section type, size, wall, grade, finish and shipment week — these parameters pass into the trade unchanged.